The proposed research will investigate the implications of high rates of union instability and repartnering for contraceptive sterilization. The investigators will first document the extent to which voluntary sterilization occurs in marriage or during periods of cohabitation and singlehood. The investigators will then conduct event-history analyses of the effects of union history and status on the risk of sterilization. These analyses will consider union formation, transition (to marriage from cohabitation) and union dissolution as processes potentially endogenous to the decision for sterilization. Where data allow, the investigators will also consider partner's sterilization as potentially endogenous to the decision to be sterilized oneself. Non-contraceptive sterilization will be treated as exogenous to contraceptive sterilization and to union formation, transition and dissolution. The investigators will use union and birth histories from nationally representative surveys of women, conducted between 1982 and 1995 in Australia, New Zealand, the United Kingdom and the United States, and from two nationally representative surveys of U.S. men. The comparative analyses will identify common patterns in societies that have undergone similar changes in union formation/dissolution and fertility and that have relatively high rates of contraceptive sterilization. Potential differences across countries in the relationships between union processes and sterilization will be linked to variations in the fertility control regime, provision of social welfare and gender equality.